People with blue skin are fun of nature, but in many cases this oddity can be given a biological explanation. Thus, abnormalities in genetic development, caused by closely related interbreeding that continued for several decades, gave the skin of some South American Indians a bluish tint.
A similar result on the skin can be obtained with some diseases. For example, in the Chilean Andes, physiologist and rock climber John West of the University of California School of Medicine met a small group of people with a blue skin tone. They turned out to be mining workers, whose cover, due to labor at an altitude of 6 thousand meters, with a constant lack of oxygen, turned blue. Obviously, a lot of hemoglobin is formed in the body of these people, which controls the distribution of oxygen in the blood. An excess of hemoglobin gives the skin a blue tint. People working under these conditions have larger lung volumes and faster breathing than others.
Other conditions in which the skin can turn blue are methemoglobinemia and argyria (argyrosis). A condition of the body in which the ability of the blood to carry oxygen to organs decreases is called methemoglobinemia. Lack of oxygen in the blood causes the skin to appear blue. Argyria results from prolonged use of silver salts, usually for medicinal purposes. Excessive use of silver salts leads to death.
Methemoglobinemia may result from the use of certain drugs or may be inherited from parents through a recessive gene. Throughout history, there have been reports of families or entire tribes with blue skin, which can be attributed to cases of hereditary methemoglobinemia.
The most famous blue-skinned family is the Fugates family from the remote area of the US state of Kentucky.
They are descendants of a French immigrant who settled there over 160 years ago. Since then, for many generations, they have only married members of their own family, and weddings outside this rule were very rare. As a result, the mutated gene was passed from generation to generation and fixed the trait - blue skin. The bodies of these people lack the enzyme needed to convert the blue protein in the blood into red hemoglobin. This gives their skin a bluish tint.